Use stable version of NixOS for nixpkgs

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

flake.lock

@@ -5,11 +5,11 @@
         "systems": "systems"
       },
       "locked": {
-        "lastModified": 1694529238,
-        "narHash": "sha256-zsNZZGTGnMOf9YpHKJqMSsa0dXbfmxeoJ7xHlrt+xmY=",
+        "lastModified": 1731533236,
+        "narHash": "sha256-l0KFg5HjrsfsO/JpG+r7fRrqm12kzFHyUHqHCVpMMbI=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "ff7b65b44d01cf9ba6a71320833626af21126384",
+        "rev": "11707dc2f618dd54ca8739b309ec4fc024de578b",
         "type": "github"
       },
       "original": {
@@ -20,16 +20,16 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1701068326,
-        "narHash": "sha256-vmMceA+q6hG1yrjb+MP8T0YFDQIrW3bl45e7z24IEts=",
+        "lastModified": 1766736597,
+        "narHash": "sha256-BASnpCLodmgiVn0M1MU2Pqyoz0aHwar/0qLkp7CjvSQ=",
         "owner": "nixos",
         "repo": "nixpkgs",
-        "rev": "8cfef6986adfb599ba379ae53c9f5631ecd2fd9c",
+        "rev": "f560ccec6b1116b22e6ed15f4c510997d99d5852",
         "type": "github"
       },
       "original": {
         "owner": "nixos",
-        "ref": "nixos-unstable",
+        "ref": "nixos-25.11",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,6 +1,6 @@
 {
   inputs = {
-    nixpkgs.url = "github:nixos/nixpkgs/nixos-unstable";
+    nixpkgs.url = "github:nixos/nixpkgs/nixos-25.11";
     flake-utils.url = "github:numtide/flake-utils";
   };
   outputs = { self, nixpkgs, flake-utils }: